It is known to produce siding from thermoplastic resin materials and for this purpose extrusion techniques have been employed in accordance with which the resin material in plasticated form is extruded through a die orifice generally conforming with the cross sectional shape of the siding, after which the extruded siding is cooled to harden it. Thereafter appropriate lengths are cut from the hardened extrusion and various machining operations are applied. In operations of the kind above referred to, it is also known to utilize polyvinyl chloride resin materials, usually formulated with pigment and other constituents to impart special properties to the product.
The present invention is concerned with a number of improvements in a technique of the general kind just referred to, which improvements are adapted to facilitate the production of the siding and are also adapted to improve the characteristics of the siding in several respects.
For example, in accordance with prior techniques, the siding produced has frequently been characterized by a high gloss surface on the face or exposed side of the siding, and this is undesirable for at least most uses for such siding. Moreover, a wood or grain texture has been imparted to various prior sidings of the kind referred to, but notwithstanding such texture effects, the siding still retained the undesired high gloss or high light reflection and, in addition, the technique of imparting the grain texture has heretofore frequently resulted in loss of impact strength.
Major objects of the present invention are to overcome the foregoing difficulties and disadvantages and to provide a method and apparatus for production of siding from thermoplastic resin materials, especially polyvinyl chloride resin materials, which siding not only has a grain texture effect but which is further characterized by low gloss and high impact strength.
Still further objects of the present invention are to provide a method and apparatus characterized by exceptionally smooth and reliable operation, production of the siding without undesired ripple effects, and maintenance of a high degree of accuracy in the shaping of the siding and also in machining operations including, for example, the cut off, the punching of nail and weep holes, and the corner notching for facilitating overlapping and interengagement of siding pieces when installed.
How the foregoing and other objects and advantages are attained will appear more fully from the following description referring to the accompanying drawings, in which: